diff --git a/Sda1/Etest/RdbmsStudents2xml/exercise1.xhtml b/Sda1/Etest/RdbmsStudents2xml/exercise1.xhtml
new file mode 100644
index 0000000000000000000000000000000000000000..6435c6733e41c217b389eef22969861b361bbaae
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/exercise1.xhtml
@@ -0,0 +1,38 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml">
+ <head>
+ <title>Exercise 1</title>
+ </head>
+
+ <body><h2>Objective</h2><p>Transforming a relational into an XML
+ schema</p><h2>Preparations / Description</h2><ol>
+ <li>Download <a
+ href="/iliasData/goik/rdbmsStudents2xml_zcx9sazr3FFDS_++vcds/rdbmsStudents2xml.zip">rdbmsStudents2xml.zip</a>
+ and import it as a project into your Eclipse workspace.</li>
+
+ <li><p>Your imported project <code>rdbmsstudent2xml</code>
+ contains:</p><ul>
+ <li><p><strong><code>Schema/schema.sql</code> describing university
+ data:</strong></p><ul>
+ <li>A relational schema consisting of two related tables
+ <code>StudyCourse</code> and <code>Student</code>.</li>
+
+ <li><code>INSERT</code> statements providing sample data.</li>
+ </ul></li>
+
+ <li><p><strong><code>Schema/testdata.xml</code> corresponding to the
+ previously mentioned relational data being contained in
+ <code>Schema/schema.sql</code>.</strong></p></li>
+
+ <li><p><strong> <code>Schema/university.xsd</code>, a sample XML
+ schema to be extended</strong></p></li>
+ </ul></li>
+ </ol><h2>ToDo</h2><p>Complete <code>Schema/university.xsd</code> to match
+ all integrity constraints of the corresponding relational
+ <code>Schema/schema.sql</code>. The XML sample
+ <code>Schema/testdata.xml</code> may guide you but may be misleading, too:
+ Examine the two <code>CREATE TABLE</code> statements thoroughly in order to
+ find all data integrity constraints.</p><p>On completion upload your file
+ <code>university.xsd</code> to the exam system.</p></body>
+</html>
diff --git a/Sda1/Etest/RdbmsStudents2xml/exercise2.xhtml b/Sda1/Etest/RdbmsStudents2xml/exercise2.xhtml
new file mode 100644
index 0000000000000000000000000000000000000000..8d11eeff15fa30b4ccbad425b4f09184b02b473b
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/exercise2.xhtml
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml">
+ <head>
+ <title>Exercise 2</title>
+ </head>
+
+ <body><h2>Objective</h2><p>Transforming relational data into XML
+ output.</p><h2>Preparations / Description</h2><ol>
+ <li>Download <a
+ href="/iliasData/goik/rdbmsStudents2xml_zcx9sazr3FFDS_++vcds/rdbmsStudents2xml.zip">rdbmsStudents2xml.zip</a>
+ and import it as a project into your Eclipse workspace.</li>
+
+ <li><p>Your imported project <code>rdbmsstudent2xml</code>
+ contains:</p><ul>
+ <li><p><strong><code>Schema/schema.sql</code> describing university
+ data:</strong></p><ul>
+ <li>A relational schema consisting of two related tables
+ <code>StudyCourse</code> and <code>Student</code>.</li>
+
+ <li><code>INSERT</code> statements providing sample data.</li>
+ </ul></li>
+
+ <li><p><strong>A driver class
+ <code>de.hdm_stuttgart.mi/sda1.sql2catalog.Rdbms2Xml</code>:</strong></p><p>On
+ Java execution this class currently just produces:</p><pre><university>
+ <studyCourses/>
+ <students/>
+</university></pre></li>
+
+ <li><p><strong><code>Schema/testdata.xml</code> corresponding to the
+ previously mentioned relational data being contained in
+ <code>Schema/schema.sql</code>.</strong></p></li>
+ </ul></li>
+ </ol><h2>ToDo</h2><p>Extend
+ <code>de.hdm_stuttgart.mi/sda1.sql2catalog.Rdbms2Xml</code> to generate
+ suitable XML data from relational sources. Data being contained in
+ <code>Schema/schema.sql</code> shall for example be transformed to
+ <code>Schema/testdata.xml</code>. But off course your implementation is
+ expected to work for arbitrary relational data input being consistent with
+ the current relational schema.</p><p>It might be a good idea to extend class
+ <code>de.hdm_stuttgart.mi.sda1.sql2catalog.RdbmsAccess</code> implementing a
+ database access layer.</p><p>On completion export your project as a
+ <code>.zip</code> file and upload it. Only the last uploaded file will
+ become subject to marking.</p></body>
+</html>
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/.gitignore b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/.gitignore
new file mode 100644
index 0000000000000000000000000000000000000000..660be2a5fdb9e3019ef8fc737d47fba56fc32ff3
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/.gitignore
@@ -0,0 +1,5 @@
+.project
+.classpath
+/.settings/
+/target/
+A1.log
\ No newline at end of file
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/schema.sql b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/schema.sql
new file mode 100644
index 0000000000000000000000000000000000000000..3f3d2c86f8eba5f7f682d060d9b8a04a2b77b8d9
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/schema.sql
@@ -0,0 +1,33 @@
+DROP TABLE IF EXISTS Student;
+DROP TABLE IF EXISTS StudyCourse;
+
+CREATE TABLE StudyCourse (
+ id INTEGER NOT NULL PRIMARY KEY
+ ,name VARCHAR(255) NOT NULL
+ ,shortName CHAR(3)
+ ,program CHAR(1) /* Bachelor or Master program? */
+ ,CHECK (program IN ('B', 'M')) /* Mysql does not really honour CHECK constraints, but pretend it does! */
+) ENGINE=InnoDB;
+
+
+CREATE TABLE Student (
+ id INTEGER NOT NULL PRIMARY KEY
+ ,fullName VARCHAR(255) NOT NULL
+ ,email VARCHAR(255) NOT NULL UNIQUE
+ ,studyCourse INTEGER
+ ,FOREIGN KEY(studyCourse) REFERENCES StudyCourse(id)
+) ENGINE=InnoDB;
+
+-- example data corresponding to university.xml --
+
+INSERT INTO StudyCourse VALUES (1, 'Mobile Media', 'MMB', 'B');
+INSERT INTO StudyCourse VALUES (2, 'Computer Science in Media', NULL, 'M');
+
+
+INSERT INTO Student VALUES(33, 'Jim Bone', 'bone@foo.org', NULL);
+INSERT INTO Student VALUES(40, 'Tracy Adams', 'adams@security.com', 2);
+
+-- Selects --
+
+SELECT * FROM Student;
+SELECT * FROM StudyCourse;
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/testdata.xml b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/testdata.xml
new file mode 100644
index 0000000000000000000000000000000000000000..342bf4f46b8a4b8a3e29c7ebf060af5c5d977f1a
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/testdata.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<university xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:noNamespaceSchemaLocation="university.xsd">
+
+ <studyCourses>
+ <studyCourse id="1" program="B">
+ <name>Mobile Media</name>
+ <shortName>MMB</shortName>
+ </studyCourse>
+ <studyCourse id="2" program="M">
+ <name>Computer Science in Media</name>
+ </studyCourse>
+ </studyCourses>
+ <students>
+ <student id="33">
+ <fullName>Jim Bone</fullName>
+ <email>bone@foo.org</email>
+ </student>
+ <student id="40" studyCourse="2">
+ <fullName>Tracy Adams</fullName>
+ <email>adams@security.com</email>
+ </student>
+ </students>
+</university>
\ No newline at end of file
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/university.xsd b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/university.xsd
new file mode 100644
index 0000000000000000000000000000000000000000..724380a5a35557681ef57f53f2e77ff172ffe2e9
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/Schema/university.xsd
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+
+ <xs:element name="university">
+
+ </xs:element>
+
+</xs:schema>
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/pom.xml b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/pom.xml
new file mode 100644
index 0000000000000000000000000000000000000000..8801a7f77c36df834719f66cc90fa8f5f2eab16b
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/pom.xml
@@ -0,0 +1,97 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+ <modelVersion>4.0.0</modelVersion>
+
+ <groupId>de.hdm-stuttgart.mi.sda1</groupId>
+ <artifactId>rdbmsstudent2xml</artifactId>
+ <version>0.8</version>
+ <packaging>jar</packaging>
+
+ <name>rdbmsstudent2xml</name>
+
+ <url>http://www.mi.hdm-stuttgart.de/freedocs</url>
+
+ <properties>
+ <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+ </properties>
+
+ <dependencies>
+ <dependency>
+ <groupId>junit</groupId>
+ <artifactId>junit</artifactId>
+ <version>4.11</version>
+ <scope>test</scope>
+ </dependency>
+
+ <dependency>
+ <groupId>org.apache.logging.log4j</groupId>
+ <artifactId>log4j-api</artifactId>
+ <version>2.1</version>
+ </dependency>
+ <dependency>
+ <groupId>org.apache.logging.log4j</groupId>
+ <artifactId>log4j-core</artifactId>
+ <version>2.1</version>
+ </dependency>
+
+ <dependency>
+ <groupId>org.jdom</groupId>
+ <artifactId>jdom2</artifactId>
+ <version>2.0.5</version>
+ </dependency>
+
+ <dependency>
+ <groupId>mysql</groupId>
+ <artifactId>mysql-connector-java</artifactId>
+ <version>5.1.34</version>
+ </dependency>
+
+ </dependencies>
+
+ <build>
+ <plugins>
+
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-compiler-plugin</artifactId>
+ <version>3.1</version>
+ <configuration>
+ <source>1.8</source>
+ <target>1.8</target>
+ </configuration>
+ </plugin>
+
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-javadoc-plugin</artifactId>
+ <version>2.10.1</version>
+ <configuration />
+ </plugin>
+
+ <plugin>
+ <groupId>org.apache.maven.plugins</groupId>
+ <artifactId>maven-shade-plugin</artifactId>
+ <version>2.3</version>
+ <configuration>
+ <transformers>
+ <transformer
+ implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
+ <manifestEntries>
+ <Main-Class>de.hdm_stuttgart.mi.sda1.catalog2sax.App</Main-Class>
+ </manifestEntries>
+ </transformer>
+ </transformers>
+ </configuration>
+ <executions>
+ <execution>
+ <phase>package</phase>
+ <goals>
+ <goal>shade</goal>
+ </goals>
+ </execution>
+ </executions>
+ </plugin>
+
+ </plugins>
+ </build>
+</project>
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Helper.java b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Helper.java
new file mode 100644
index 0000000000000000000000000000000000000000..f7879587615344dbd2eef926cfb7b55f4a0c451e
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Helper.java
@@ -0,0 +1,18 @@
+package de.hdm_stuttgart.mi.sda1.sql2catalog;
+
+/**
+ * Project wide helper methods
+ *
+ */
+public class Helper {
+ /**
+ * Write message to stderr and exit with given error code
+ * @param errMsg
+ * @param errorCode
+ */
+ public static void exitWithErrorMessage(final String errMsg, int errorCode) {
+ System.err.println(errMsg);
+ System.exit(errorCode);
+ }
+
+}
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Rdbms2Xml.java b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Rdbms2Xml.java
new file mode 100644
index 0000000000000000000000000000000000000000..f733fc76c3d903baafdcb2fc9f7d75a7fde95bc1
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/Rdbms2Xml.java
@@ -0,0 +1,58 @@
+package de.hdm_stuttgart.mi.sda1.sql2catalog;
+
+import java.io.IOException;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+import org.jdom2.Element;
+import org.jdom2.output.Format;
+import org.jdom2.output.XMLOutputter;
+
+/**
+ * A simple SAX parser demo
+ *
+ */
+public class Rdbms2Xml {
+
+ /**
+ * @param args Unused
+ */
+ public static void main(String[] args) {
+
+ // Register Driver
+ final String sqlDriverClassName = "com.mysql.jdbc.Driver";
+ try {
+ Class.forName(sqlDriverClassName);
+ } catch (ClassNotFoundException e) {
+ Helper.exitWithErrorMessage("Unable to register driver class '" + sqlDriverClassName + "'", 1);
+ }
+
+ // Opening a JDBC connection
+ //
+ Connection conn = null;
+
+ final String jdbcConnectionUrl = "jdbc:mysql://localhost:3306/hdm";
+ final String userName = "hdmuser";
+ try {
+ conn = DriverManager.getConnection(jdbcConnectionUrl, userName, "XYZ");
+ } catch (SQLException e) {
+ Helper.exitWithErrorMessage("Unable to connect as user '" + userName + "' to '" +
+ jdbcConnectionUrl + "'", 1);
+ }
+
+ final Element universityElement = new Element("university");
+ final Element studyCourses = new Element("studyCourses");
+ universityElement.addContent(studyCourses);
+ final Element students = new Element("students");
+ universityElement.addContent(students);
+
+ // Write XML content to standard output
+ XMLOutputter outputter = new XMLOutputter(Format.getPrettyFormat());
+ try {
+ outputter.output(universityElement, System.out);
+ } catch (IOException e) {
+ Helper.exitWithErrorMessage("Unable to write XML data:" + e.getLocalizedMessage(), 1);
+ }
+ }
+}
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/RdbmsAccess.java b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/RdbmsAccess.java
new file mode 100644
index 0000000000000000000000000000000000000000..740a996a2fb8aac9d4cf5f95a9fc46b65d967027
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/java/de/hdm_stuttgart/mi/sda1/sql2catalog/RdbmsAccess.java
@@ -0,0 +1,18 @@
+package de.hdm_stuttgart.mi.sda1.sql2catalog;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+
+/**
+ * Reading study course and student data
+ *
+ */
+public class RdbmsAccess {
+
+ /**
+ * @param conn Destination RDBMS
+ */
+ public RdbmsAccess(final Connection conn) {
+ }
+
+}
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/resources/log4j2.xml b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/resources/log4j2.xml
new file mode 100644
index 0000000000000000000000000000000000000000..eda4f3b0d781b09217fb4218285c39adf8d3c9c0
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml/src/main/resources/log4j2.xml
@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Configuration>
+ <Appenders>
+ <File name="A1" fileName="A1.log" append="false">
+ <PatternLayout pattern="%t %-5p %c{2} - %m%n"/>
+ </File>
+ <Console name="STDOUT" target="SYSTEM_OUT">
+ <PatternLayout pattern="%C{2} (%F:%L) - %m%n"/>
+ </Console>
+ </Appenders>
+ <Loggers>
+
+ <!-- You my want to define class or package level per-logger rules -->
+ <Logger name="de.hdm_stuttgart.mi.sda1.catalog2sax.App" level="debug">
+ <AppenderRef ref="A1"/>
+ </Logger>
+ <Root level="debug">
+ <AppenderRef ref="STDOUT"/>
+ </Root>
+ </Loggers>
+</Configuration>
\ No newline at end of file
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/schema.sql b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/schema.sql
index 3f3d2c86f8eba5f7f682d060d9b8a04a2b77b8d9..5867d4df1ddfd5b832ec41fa35fa8ca2fa99ee4f 100644
--- a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/schema.sql
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/schema.sql
@@ -3,13 +3,12 @@ DROP TABLE IF EXISTS StudyCourse;
CREATE TABLE StudyCourse (
id INTEGER NOT NULL PRIMARY KEY
- ,name VARCHAR(255) NOT NULL
- ,shortName CHAR(3)
+ ,name VARCHAR(255) NOT NULL UNIQUE
+ ,shortName CHAR(3) UNIQUE
,program CHAR(1) /* Bachelor or Master program? */
,CHECK (program IN ('B', 'M')) /* Mysql does not really honour CHECK constraints, but pretend it does! */
) ENGINE=InnoDB;
-
CREATE TABLE Student (
id INTEGER NOT NULL PRIMARY KEY
,fullName VARCHAR(255) NOT NULL
@@ -23,7 +22,6 @@ CREATE TABLE Student (
INSERT INTO StudyCourse VALUES (1, 'Mobile Media', 'MMB', 'B');
INSERT INTO StudyCourse VALUES (2, 'Computer Science in Media', NULL, 'M');
-
INSERT INTO Student VALUES(33, 'Jim Bone', 'bone@foo.org', NULL);
INSERT INTO Student VALUES(40, 'Tracy Adams', 'adams@security.com', 2);
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/testdata.xml b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/testdata.xml
new file mode 100644
index 0000000000000000000000000000000000000000..342bf4f46b8a4b8a3e29c7ebf060af5c5d977f1a
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/testdata.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<university xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+ xsi:noNamespaceSchemaLocation="university.xsd">
+
+ <studyCourses>
+ <studyCourse id="1" program="B">
+ <name>Mobile Media</name>
+ <shortName>MMB</shortName>
+ </studyCourse>
+ <studyCourse id="2" program="M">
+ <name>Computer Science in Media</name>
+ </studyCourse>
+ </studyCourses>
+ <students>
+ <student id="33">
+ <fullName>Jim Bone</fullName>
+ <email>bone@foo.org</email>
+ </student>
+ <student id="40" studyCourse="2">
+ <fullName>Tracy Adams</fullName>
+ <email>adams@security.com</email>
+ </student>
+ </students>
+</university>
\ No newline at end of file
diff --git a/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/university.xsd b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/university.xsd
new file mode 100644
index 0000000000000000000000000000000000000000..519f8962184e839d5da5f7e07a8a5a3e3bdf7b3f
--- /dev/null
+++ b/Sda1/Etest/RdbmsStudents2xml/rdbmsStudents2xml_solution/Schema/university.xsd
@@ -0,0 +1,81 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+
+ <xs:element name="studyCourse">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element name="name" type="xs:string"/>
+ <xs:element name="shortName" minOccurs="0">
+ <xs:simpleType>
+ <xs:restriction base="xs:string">
+ <xs:maxLength value="3"/>
+ </xs:restriction>
+ </xs:simpleType>
+ </xs:element>
+ </xs:sequence>
+ <xs:attribute name="id" type="xs:int" use="required"/>
+ <xs:attribute name="program">
+ <xs:simpleType>
+ <xs:restriction base="xs:string">
+ <xs:enumeration value="B"/>
+ <xs:enumeration value="M"/>
+ </xs:restriction>
+ </xs:simpleType>
+ </xs:attribute>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="studyCourses">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="studyCourse" minOccurs="0" maxOccurs="unbounded"/>
+ </xs:sequence>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="student">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element name="fullName" type="xs:string"/>
+ <xs:element name="email" type="xs:string"/>
+ </xs:sequence>
+ <xs:attribute name="id" type="xs:int" use="required"/>
+ <xs:attribute name="studyCourse" type="xs:int" use="optional"/>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="students">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="student" minOccurs="0" maxOccurs="unbounded"/>
+ </xs:sequence>
+ </xs:complexType>
+ </xs:element>
+
+ <xs:element name="university">
+ <xs:complexType>
+ <xs:sequence>
+ <xs:element ref="studyCourses"/>
+ <xs:element ref="students"/>
+ </xs:sequence>
+ </xs:complexType>
+
+ <xs:key name="uniqueStudyCourse">
+ <xs:selector xpath="studyCourses/studyCourse"/>
+ <xs:field xpath="@id"/>
+ </xs:key>
+
+ <xs:keyref refer="uniqueStudyCourse" name="studyCourse2student">
+ <xs:selector xpath="students/student"/>
+ <xs:field xpath="@studyCourse"/>
+ </xs:keyref>
+
+ <xs:key name="uniqueStudent">
+ <xs:selector xpath="students/student"/>
+ <xs:field xpath="@id"/>
+ </xs:key>
+
+ </xs:element>
+
+
+</xs:schema>